Filament for electric incandescent lamps and process of making the same.



- full, clear, and ex down to 83 per The varying results of the analysis might UNITE STAS HANS KUZEL, or BADEN,NEAR VIENNA, AUSTRIA-HUNGARY.

FILAMENT FOR ELECTRIC monnbzasonmr LAMPS ANDPROCESS OF MAKING.

THE SAME.

Specification of Letters Patent.

-Patented Aug. 11, 1908.

' Application filed May 7, 1907. Serial No. 372,354.

To all whom it may concern:

Be it known that I, HANS K ZEL, a subject of the Emperor of Germany, and a resident of Baden, near Vienna, Empireof Austria-Hungary, have invented certain new and useful Improvements inFilaments for Eleotr'ic Incandescent Lamps and Processes of Making the Same, of which the following is a 'act specification.

According to H. Schulze (J oumal fur Prekt'ische Oliemie, XXXII, page 399) colloidal tungstenis obtained by. reducing tungstic trioxid with potassium cyanid'. But from a paper of Desi (Journal of the American Chemtcal Society, 1897, -)age 239 and the following) it is seen that t e'reaction goes on differently according to the temperature inaintained. On the one hand at the most,in

tense white heat the reaction leads to crystalline 'or molten tungsten, whileon the other hand when working at as low a'red heat as possible, an oxynitrid in the form of black powder is obtained, the exact composition of which could not be found. By heating tungstic trioxid with sal ammonia, Desi obtained the same oxynitrids (l. 0. page 236 and the following) which likewise could not be.de-

.fined exactly. According to the temperature at which the reaction was carried out the black bodies obtained showed, when analyzed, a varying percentage of tungsten,

cent. and even less.

possibly be explained by assuming that when working at low temperatures besides an oxynitrid of a well defined composition, there is produced simultaneously therewith always a larger or smaller amount of colloidal tungsten. I have 'found that these black substances containingoxynitrids of tungsten are partly already in the colloidal state, and

that they may be readily converted com-- pletely into the colloidal state by the method of my patent,871,599, Nov. 19, 1907, which consists in"tre.ating the most finely comminuted substance alternately with solutions of an acid and a non-acid character under thorough agitation and also heatingto a temper-. ature not exceeding 100 centigrade.

The object=of my present invention is to I utilize these black more or less colloidal products containing oxynitrids for manufacturing filaments;

The substance obtained as above described in a more or less completelycolloidal state is worked into a plastic mass in the known mannereither by removing therefrom any superfiuousimbibition liquid by cautious evaporationor by pressu1e or by incorporating into the substance the required quantity of imbithorough mixing and agit'aj bition liquid by tion or kneadin I ,From the plastic mass thus obtained threads are made in any known manner, preferably by squirting these threads containing tungsten and "colloidal oxynitrids of tungsten. They are then cautiously dried and finally gradually heated to a white heat, preferably by an electric current passed through them. The heating is efi'ected in a non-oxidizing atmosphere either in an inert or reducing gas, such as hydrogen or nitrogen, and preferably in the form of a current, or it may be in vacuo, the vacuum being maintained uniform during the heating as nearly as possible by means of an eflicient pump.

By such heating, the colloidal tungsten is converted into the crystalline state and at the same time the oxynitrids of tungsten are reduced .to tungsten, also in the crystalline state, -so that a filament consisting of pure tungsten in the crystalline state is obtained which is ready for use. This conversion is accompanied by a reduction of the diameter and. the length of the filament, this reduction being nearly twice the shrinking of pure colloidal tungsten By using the black colloids containing oxynitrids of tungsten it is therefore possible to obtain most easily much thinner filaments than byusingpure colloidal tungsten.

The great shrinkage is fairly well explained by the fact that the colloid containing oxynitrids contains only 83 Yer cent. tungsten and that these colloidal threads, as has been shown by experiment, are capable of retaining more imbibition liquid (possibly in the form of gel water which plays a part similar to that of crystal water) than the colloidal tungsten.

v The importance of this new process is clearly shown by'the fact that a necessary condition for the production of high voltage and lowcandle power lam s (110 volts and 16 candle power or 110 v0 ts and 10 candle power) is to obtain most fine filaments the diameter of which is about 0.015- to 0.02.

n'iillinmters.

I claim as my invention: g 1. A process of manufacturing partlcularly thin tungsten filaments for electric incandescent lamps, consisting in producing a Plastic mass containing tungsten and coloidal oxynitrid of tun sten, forming threads drying suc threads and finally heating such threads to a white heat in a non-oxidizing atmos here, substantially as and for the purpose ascribed.

2. As anew article of manufacture, a

[0 thread capable of being converted into a 5 therefrom,

gradually crystalline tungsten filament and containing tungsten and colloidal oxynitrid of tungtwo subscribing witnesses.

HANS KUZEL.

Witnesses: w

ARTHUR BAUMANN, Ron'r. W. HEINGARTNER. 

